Field of the Invention
The present invention relates to an image forming apparatus such as an electrophotographic copier, printer, and the like.
Description of the Related Art
The image forming apparatus forming a toner image on a recording medium has a fixing device to fix the toner image to the recording medium. A fixing device that has a first fixing member, and a second fixing member between which a nip portion fixed is formed, is used as this fixing device. A recording medium that bears a toner image is heated by the heat of the first fixing member at the nip portion, which fixes the toner image on the recording medium.
According to such a fixing device, when small size recording mediums are continuously passed, excessive temperature rise of a non-sheet-passing area through which a recording medium does not pass, i.e. a sheet non-passing area temperature rise, may occur. Conversely, Japanese Patent Laid-Open No. 2007-79040 discloses a fixing device that has a fan which is disposed near a film and blows toward the film, a shutter that is disposed between the fan and film moves according to the width of the recording medium, wherein the non-sheet-passing area of the film is cooled by the fan blowing.
However, as processing speeds continue to increase in accordance with productivity improvements, if the fixing temperature is increased accordingly, cooling the non-sheet-passing area of the fixing device with only the fan that blows toward the film, as disclosed in Japanese Patent Laid-Open No. 2007-79040 becomes difficult.
This is because when the fan size is increased and blows a greater volume of air toward the film, the air thereof may move around the shutter and cool the sheet-passing area, which may cause a fixing failure.